This invention relates to an image display method and device for use in a game device or the like and, in particular, to the image display method which is appropriate for displaying an emitted light beam, such as a flash of lightning to obtain a sufficient visual effect. In addition, this invention relates to a computer-readable storage-medium for storing a program for displaying the emitted light beam with high reality.
Conventionally, a wide variety of computer games or video games, such a simulation game, a role playing game, a battle game, a puzzle game, and the like have been proposed and become popular in the world. It is a recent trend that the users"" demands or requests for the computer games have been also diversified and varied at every one of the computer games. One of the demands or requests has been directed to displaying a moving image with high reality. Such displaying might serve to give a visual effect to the users or players, as if they would really experience events in a virtual game space.
Among these games, there is a game which displays an emitted light beam, such as a flash of lightning, traveling in a zigzag manner. In this event, it is preferable that the emitted light beam can visually display its power, which might be helpful to augment interest of the users to the game. For example, in a game which is named xe2x80x9cfantastic Suiko-denxe2x80x9d (fantastic Chinese famous story), the flash of lightning is displayed as an example of the emitted light beam and travels from an upper part to a lower part of a screen.
Conventionally, such an emitted light beam, such as the flash of lightning, has been expressed like an animation on a screen by successively displaying a plurality of bit map images in sequence. However, it is difficult to visually display a flash of lightning with reality and to visually express a wide variety of lightning. Under the circumstances, it is a recent trend that consideration is focused on simulating an actual flash of lightning.
However, it is to be noted that an actual flash of lightning is irregularly folded and separated. As a result, it is very laborious to observe irregular actual flashes of lightning and to simulate such irregular actual flashes of lightning. Practically, simulating the irregular actual flashes of lightning is not economical and can not be therefore applied to a game device because a memory capacity and a cost are restricted in such a game device.
Moreover, a faithful reproduction of the actual flash of lightning can not always display a powerful image in a virtual space within a game device. This shows that some exaggeration is needed in the virtual space to visually satisfy the users when the emitted light beam, such as the flash of lightning, is displayed by the game device.
It is an object of this invention to provide a method which is capable of displaying an emitted light beam as a powerful image in a virtual space on a screen of a display device.
It is another object of this invention to provide a method of the type described, which can display the emitted light beam with a sufficient visual effect.
It is still another object of this invention to provide a computer-readable storage medium which stores a program which can effectively display the emitted light beam, such as a flash of lightning.
It is yet another object of this invention to provide an image display device which can display the emitted light beam somewhat visually exaggerated.
According to an aspect of this invention, a method is for use in visually and virtually displaying, on a display device, an emitted light beam which travels from a start point in a zigzag manner. The method comprises the steps of determining a first reference line drawn at the start point of the emitted light beam and a final target point defining a final attainable zone, connecting the start point and the final target point by a reference zone line which is inclined at a predetermined angle with respect to the first reference line, defining a first segment which is extended from the start point at a first angle smaller than the predetermined angle towards the final target point and which represents a part of the emitted light beam from the start point, calculating a length of the first segment between the start point and a first point which follows the start point and at which the emitted light beam is folded, together with light intensity related to the first segment, determining a second segment between the first point and a second point which succeeds the first point and at which the emitted light beam is folded, so as to represent another part of the emitted light beam by the second segment, successively calculating a length, an angle, and light intensity of another part of the emitted light beam represented by the second segment on the basis of the length, the angle, and the light intensity of the first segment, and displaying the emitted light beam which falls within the final attainable zone by repeating the successive calculation of the length, the angle, and the light intensity of the emitted light beam.
According to another aspect of this invention, a computer-readable storage medium stores a program for visually and virtually displaying, on a display device, an emitted light beam which travels from a start point in a zigzag manner. The program comprises the steps of determining a first reference line drawn at the start point of the emitted light beam and a final target point defining a final attainable zone, connecting the start point and the final target point by a reference zone line which is inclined at a predetermined angle with respect to the first reference line, defining a first segment which is extended from the start point at a first angle smaller than the predetermined angle towards the final target point and which represents a part of the emitted light beam from the start point, calculating a length of the first segment between the start point and a first point which follows the start point and at which the emitted light beam is folded, together with light intensity related to the first segment, determining a second segment between the first point and a second point which succeeds the first point and at which the emitted light beam is folded, so as to represent another part of the emitted light beam by the second segment, successively calculating a length, an angle, and light intensity of another part of the emitted light beam represented by the second segment on the basis of the length, the angle, and the light intensity of the first segment, and displaying the emitted light beam which falls within the final attainable zone by repeating the successive calculation of the length, the angle, and the light intensity of the emitted light beam.
According to a further aspect of this invention, an image display device is used for in visually and virtually displaying, on a display device, an emitted light beam which travels from a start point in a zigzag manner. The image display device comprises first processing means for processing the emitted light beam, by dividing the emitted light beam into a sequence of segments each of which is folded at an end point, by determining a first reference line drawn at the start point of the emitted light beam and a final target point defining a final attainable zone, by connecting the start point and the final target point by a reference zone line which is inclined at a predetermined angle with respect to the first reference line, by defining a first segment which is extended from the start point at a first angle smaller than the predetermined angle towards the final target point and which represents a part of the emitted light beam from the start point, and by thereafter successively determining an angle, a length, and light intensity of the following segments on the basis of the angle, the length, and the light intensity calculated in connection with the segment immediately before, and by allowing a final one of the segment to pass through the final attainable zone and second processing means for putting images representative of the emitted light beam along the segments.
In this event, the first processing means varies the following angle of the next one of the segments by using a previous one of the segments as a reference line and calculates the angle, the length, and the light intensity of each segment on the condition that each length and light intensity is invariable. On the other hand, the second processing means comprises means for forming an image of the emitted light beam by putting a polygon and a texture representative of the emitted light beam, along the segments and means for adjusting a color of the image.